64 Forest Club Annual 



C2. Twigs cylindrical, pubescent or glabrous, buds dark 

 brown, scales broad ovate, apex acute. 



* F. americana Linn. 



* F. pennsylvanica Marsh. 



* F. lanceolata Borkh. 



* F. oregona Nutt. 



* F. nigra Marsh. 



73. Terminal bud one-quarter inch long, scales several 

 smooth red, distinct stipular line connects leaf-scars, 

 bundle-scars five to seven distinct, twig large glabrous 

 green changing to red during winter, leaf-scars cres- 

 cent-shaped Acer macrophyllum Pursh. 

 03. Bundle-scars many forming an ellipse. 



Catalpa (see above). 

 ///. Leaf-scars alternate, one at each node. 



ai. Bud at end of twig entirely or partially sunk in bark. 

 bi. Twigs armed with two stipular prickles, bundle-scars 

 three, buds white silky hidden beneath shield-shaped 

 leaf-scar, no terminal bud, tip-scar or dead tip of the 

 twig prominent, twig reddish brown. 



Robinia pseudacacia .Linn. 



b2. Twigs armed with simple or branched thorns above the 

 buds, several buds superposed, the lower ones hidden 

 beneath the V-shaped leaf-scar, bundle-scars three 

 prominent, no stipule-scars, no terminal bud, tip-scar 

 distinct, twig light yellowish brown glabrous. 



Gleditsia triacanthos Linn. 

 b$. Twigs without thorns or prickles. 



ci- Pith salmon colored, twigs very large, buds small 

 two superposed covered with brown hairs, no termi- 

 nal bud, tip-scar prominent, no stipule-scars, leaf-scar 

 large shield-shaped with three to five large protrud- 

 ing bundle-scars in a U-line, twig reddish brown or 

 light gray. 



Gymnocladits dioicus (Linn.) Koch. 

 C2. Pith white or yellow. 



*It is difficult to distinguish between these species without leaves or 

 fruit. A cross-section of the terminal bud of F. nigra is usually elliptical 

 and shows three pair of bud-scales, while in the case of the other four 

 species the cross-section is more or less four-lobed and usually shows 

 four scales. In the East the twigs of F. pennsylvanica are pubescent 

 and the buds small, while F. americana and F. lanceolata are glabrous 

 and the buds large, but near the Mississippi River and west of it there 

 is much confusion of these three species. The twig of F. oregona is 

 often light woolly. 



